Historians have recently discovered a historical journal published in the early twentieth century. the journal contains facts based on original sources about the downfall of the early byzantium empire. historians consider this long-lost journal to be a breakthrough in their understanding of the byzantium empire. based on this information, the journal is a
source.

That is true.

Explanation:

In the study of history as an academic discipline, a primary source (also called original source or evidence) is an artifact, a document, diary, manuscript, autobiography, a recording, or other source of information that was created at the time under study. It serves as an original source of information about the topic. Similar definitions can be used in library science, and other areas of scholarship, although different fields have somewhat different definitions. In journalism, a primary source can be a person with direct knowledge of a situation, or a document written by such a person.